def list_depth(lst):
    if isinstance(lst, list):
        max_depth = 1

        for it in lst:
            max_depth = max(list_depth(it) + 1, max_depth)
        return max_depth
    
    return 0

lst = [1,[1,2],[1,[2,[3]]]]
lst_depth = list_depth(lst)
print(lst_depth)